1. Field of the Invention
The present invention relates to an audible tone signal service apparatus and method of a digital mobile services switching center (hereinafter simply referred to as "MSC"), and more particularly to an audible tone signal service apparatus and method of a digital MSC for separately designing a board for transmitting only an audible signal in the MSC which uses a code division multiple access (CDMA) system to simplify a hard ware construction of a universal signal transceiver board assembly (hereinafter simply referred to as "USTA"), and processing 32 channels for a single USTA board.
2. Description of the Prior Art
Generally, a general signal processing apparatus used in MSC which is an exchanger of the CDMA system is a signal apparatus for processing every signal received via a time switch. As shown in FIG. 1, the general signal processing apparatus receives to process time slots in respective sub highways SHW from a time-division time switch 1 via a signal processing 0 group USTU 0 and a signal processing 1 group USTU1, respectively, and reports the result of the processing to first and second higher processors 3 and 4 via a telephony device-BUS (hereinafter referred to as TD-BUS). Then, an alarm collecting apparatus 2 connected to respective signal processing groups collects for processing information about the various alarms such as an alarm for warning of an error generated in the USTA board of respective groups, i.e., detachment of the USTA board, while the time slot is provided to respective signal processing groups and an alarm warning of a functional impedient.
The internal construction of the USTA board installed within the general signal processing apparatus is as illustrated in FIG. 2. Here, a pulse code modulation (hereinafter simply referred to as "PCM") data input circuit 5 receives an R2 multi-frequency code (hereinafter referred to as "MFC") provided from the time switch, a dual tone multi frequency (hereinafter referred to as DTMF) signal and continuity check tone (hereinafter referred to as CCT) signals to perform PCM data processing. A clock generator 6 generates clocks to provide a clock required the digital signal processor. A first processing section 7 for processing 8 channel with respect to 16 channel from PCM data input circuit 5 consists of a first digital signal processor 7-1 which receives to detect the signal output via PCM data input circuit 5, and produces signal information with respect to the output signal into a first input/output memory 7-2 which receives the data from first digital signal processor 7-1 to inform a higher processor of the result via a control block, and an EPROM 7-3 which includes a control program therein for controlling first digital signal processor 7-1. Also, a second processing section 8 is identically constructed to first processing section 7 to process the remaining 8 channels with respect to the input 16 channels.
Respective digital signal processors (DSP) 7-1 and 8-1 employed as above adopt `TMS320C25`, which respectively detect 8 channels with respect to respective R2 MFC, DTMF and CCT signals for each chip of DSPs 7-1 and 8-1 and number two per one sheet of the USTA board to function the signal processing service of 16 channels (i.e., 2 (number of DSP)=8 channels=16 channels).
Respective board assemblies (USTAs) of the signal processing apparatus constructed as above are controlled by the higher processor with respect to the signal service function of R2 MFC, DTMF signal, CCT signal tone and audible signal tone to generate a signal to the time switch while detecting and discriminating the signal received from the time switch.
However, the signal processing apparatus functioning as above is formed as the general system as shown in FIG. 1. Therefore, when performing the transmitting service of the audible signal tone, digital signal processors 7-1 and 8-1, I/O memories 7-2 and 8-2, receiving section are not required in actual practice, but are employed due to the USTA structure in spite of the unnecessary function.